600 Messrs. G. M. Mathews and T. Iredale on so7ne 



Zealand bird does not wander to California : such a state- 

 ment would seem absurd. All birds from the Indian Ocean, 

 western and eastern Australia, and southern Pacific are uni- 

 formly dark. From Laysan comes a white-bellied form with 

 a few uniform birds intermingled, while on San Benedicto 

 Island, oflF the Mexican coast, a uniform bird occurs with a 

 light-breasted one, the dark bird predominating. From the 

 Pescadores Islands a single light-breasted bird has been 

 received, almost certainly a breeding individual, and it is 

 very probable that only white-breasted birds of this group 

 occur on the Islands, as dark birds received prove to belong 

 to Neonectris griseus (Gmelin) subsp. 



The apparent variation in coloration observed at San 

 Benedicto Island and Laysan is quite unparalleled in this 

 family, and is more puzzling than in the case of ^strelata 

 neglecta Schlegel, with whose phases one of us is very 

 familiar. In that case we have a variable species at three 

 or four different localities with nothing very similar other- 

 wise known. In the present case we have two very distinct 

 species, quite constant, found in many localities, and then a 

 commingling of the two on one or two groups of islands in 

 different ratios. This strongly suggests hybridism and the 

 separation of the two as distinct species. Adopting this view 

 we would therefore restrict Pvffinus pacificus alleni Mathews 

 (Birds Austr. vol. ii. 1912, p. 83) to the dark birdj and note 

 the forms of T. cuneaia as follows : — 



Thyelludroma cuneata cuneuta Salvin. 



Marshall group, Vulcan group, Bonin Island, 



Pescadores Islands. 



T. c. laysani Mathews. Laysan, Hawaiian Group. 



T. c. subsp. San Benedicto Island, Mexico. 



Genus Neonectris. 

 Neonectris Mathews, Austral Av. Rec. vol. ii. 1913, p. 12. 

 Type (by original designation) : Puiffinus brevicaudus 

 Gould. 



This name was proposed by Mathews as the names used 



